The examination of mental disorders would seem to be the almost exclusive domain of psychiatrists and psychologists, not humanities scholars. Yet William V. Harris, the William R. Shepherd Professor of History, has spent his time in recent years studying his chosen field—the history of ancient Greece and Rome—through the lens of mental illness.

Harris, director of the Columbia Center for the Ancient Mediterranean, has explored subjects in ancient times ranging from war and imperialism to literacy and economic history. More recently, he began to focus on emotional states...